diff --git a/README.md b/README.md
index 6031859..e9538ea 100644
--- a/README.md
+++ b/README.md
@@ -111,14 +111,23 @@ Place these sounds in the folder `system` on the SD card:
 sleep.mp3 will be played just before the timed shutdown, start.mp3 will be played if the box started and initialized successfully.
 
 
+## Battery Voltage
+
+The battery voltage is measured by the ADC of pin 13. A voltage divider halves the voltage so that the pin can not be overloaded (max 3.3V).
+The voltage divider consists of two 100kOHM resistors, the voltage is measured between them. One side is connected to the battery and the other to ground.
+Pin 13s ADC (ADC2) can not be used while WIFI is on... damn.
+
 ## TODOs
+
 * Card Reader with SPI. Configure hspi, second SPI channel? Or does SD Card + RFID run at the same channel?
 
 ![](images/wemos-d1-mini-esp32.png)
 
 
 ## Schematic without modules
+
 ### Charging circuit
+
 https://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf
 MCP73837 ?
 
diff --git a/src/WebContent.h b/src/WebContent.h
index 9746fc8..702b75f 100644
--- a/src/WebContent.h
+++ b/src/WebContent.h
@@ -9,6 +9,8 @@ const char index_html[] PROGMEM = R"rawliteral(
   <body>
     <h1>HannaBox</h1>
     <span id="state"></span><br/><br/>
+    <span id="voltage"></span><br/>
+    <span id="uid"></span><br/>
 
 <div>
     <button class="prev-button" onclick="simpleGetCall('prev');""></button>
@@ -16,16 +18,17 @@ const char index_html[] PROGMEM = R"rawliteral(
     <button class="next-button" onclick="simpleGetCall('next');"></button><br/><br/>
 </div>   
   <div class="slidecontainer">
-    <label for="progress" id="progressLabel"></label>
+    
     <input name="progress" type="range" min="0" max="100" value="0" class="slider" id="progressSlider" 
-    onmouseup="postValue('progress',document.getElementById('progressSlider').value);"
-    ontouchend="postValue('progress',document.getElementById('progressSlider').value);">
+    onchange="postValue('progress',document.getElementById('progressSlider').value);lastChange = Date.now()"
+    >
+    <label for="progress" id="progressLabel"></label>
   </div>
-  <div class="slidecontainer">
-    <label for="volume">Vol</label>
+  <div class="slidecontainer">    
     <input name="volume" type="range" min="0" max="15" value="7" class="slider" id="volumeSlider" 
-    onmouseup="postValue('volume',document.getElementById('volumeSlider').value);"
-    ontouchend="postValue('volume',document.getElementById('volumeSlider').value);">
+    onchange="postValue('volume',document.getElementById('volumeSlider').value);lastChange = Date.now()"
+    >
+    <label for="volume">Vol</label>
   </div> 
 <!--
     <button onmouseup="simpleGetCall('stop');" ontouchend="simpleGetCall('stop');">Stop</button>&nbsp; 
@@ -42,6 +45,8 @@ const char index_html[] PROGMEM = R"rawliteral(
     // Get the <li> elements
     var liElements = document.querySelectorAll('ul li');
 
+    var lastChange = 0;
+
     // Add click event listener to each <li> element
     liElements.forEach(function(li) {
       li.addEventListener('click', function() {
@@ -81,6 +86,8 @@ const char index_html[] PROGMEM = R"rawliteral(
    function displayState(state) {
     document.getElementById("state").innerHTML = state['title'];
     document.getElementById("progressLabel").innerHTML = state['time'];
+    document.getElementById("voltage").innerHTML = state['voltage']+' mV';
+    document.getElementById("uid").innerHTML = 'Last NFC ID: '+state['uid'];
     var elements = document.getElementsByClassName('play-button');
     var btn = elements[0];
 
@@ -89,12 +96,16 @@ const char index_html[] PROGMEM = R"rawliteral(
     } else {
       btn.classList.remove('paused');
     }
-    var progress = document.getElementById('progressSlider');
-    progress.value = state['time'];
-    progress.max = state['length'];
+    
+    if (Date.now()-lastChange>1200) {
+      var progress = document.getElementById('progressSlider');
+      progress.value = state['time'];
+      progress.max = state['length'];
+
+      var volume = document.getElementById('volumeSlider');
+      volume.value = state['volume'];
+    }
 
-    var volume = document.getElementById('volumeSlider');
-    volume.value = state['volume'];
 
    }
 
diff --git a/src/css.h b/src/css.h
index c272cd5..f1a22e2 100644
--- a/src/css.h
+++ b/src/css.h
@@ -65,4 +65,8 @@ li {
   box-shadow: -10px 0 0 0 darkgrey;
 }
 
+.slider {
+  width: 80%;
+}
+
 )rawliteral";
\ No newline at end of file
diff --git a/src/globals.h b/src/globals.h
index e2e056c..2e82dd9 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -52,6 +52,7 @@ void writeFile(fs::FS &fs, const char * path, const char * message){
   file.close();
 }
 
+
 unsigned long lastStart = 0;
 
 unsigned long lastInteraction =  0;
@@ -64,12 +65,20 @@ boolean continuousMode = false;
 
 uint8_t buttontoignore = 0;
 
+uint32_t lastVoltage = 0;
+
 const int startDelay = 250;
 
+String lastUid = "";
+
 const String sleep_sound = "sleep.mp3";
 
 const String startup_sound = "start.mp3";
 
+const String mapping_file = "/mapping.txt";
+
+std::map<String, String> rfid_map;
+
 /*
 const long sleepMessageDelay = 28000;
 
diff --git a/src/main.cpp b/src/main.cpp
index a9520ed..adc7fac 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -31,6 +31,8 @@
 
 #define CS_SDCARD 22
 
+#define BAT_VOLTAGE_PIN 13
+
 #define RFID_LOOP_INTERVAL 25
 
 #include "globals.h"
@@ -75,9 +77,12 @@ bool asyncNext = false;
 
 bool asyncPrev = false;
 
+/*
 std::map<String, String> rfid_map{{"67 152 204 14", "01-The_Box_Tops-The_Letter.mp3"},
                                   {"67 175 148 160", "068-Der_Schatz_im_Bergsee"}};
 
+*/                                  
+
 void activateSD()
 {
   digitalWrite(CS_SDCARD, LOW);
@@ -98,6 +103,12 @@ void deactivateRFID()
   digitalWrite(CS_RFID, HIGH);
 }
 
+uint32_t getBatteryVoltageMv() {
+  uint32_t voltage = analogReadMilliVolts(BAT_VOLTAGE_PIN);
+  return voltage*2;//*2 because of the voltage divider.
+}
+
+
 void playSongByName(String song)
 {
   currentNode = rootNode.advanceToMP3(&song);
@@ -117,10 +128,14 @@ void playSongByPath(String path)
 
 void playSongByRFID(String id)
 {
-  String song = rfid_map[id];
+  auto songit = rfid_map.find(id);
+  if (songit==rfid_map.end()) {
+    Serial.println("song for uid not found.");
+    return;
+  }
   Serial.println("searching for ");
-  Serial.println(song);
-  playSongByName(song);
+  Serial.println(songit->second);
+  playSongByName(songit->second);
 }
 
 /**
@@ -200,11 +215,41 @@ String getState()
   jsonState["time"] = audio.getAudioCurrentTime();
   jsonState["volume"] = audio.getVolume();
   jsonState["length"] = audio.getAudioFileDuration();
+  jsonState["voltage"] = lastVoltage;
+  jsonState["uid"] = lastUid;
   String output;
   serializeJson(jsonState, output);
+  jsonState.clear();
+  jsonState.garbageCollect();
   return output;
 }
 
+std::map<String, String> readDataFromFile(const char *filename) {
+  
+  File file = SD.open(filename);
+
+  if (file) {
+    while (file.available()) {
+      // Read key and value from the file
+      String line = file.readStringUntil('\n');
+      int separatorIndex = line.indexOf('=');
+      if (separatorIndex != -1) {
+        // Extract key and value
+        String key = line.substring(0, separatorIndex).c_str();
+        String value = line.substring(separatorIndex + 1).c_str();
+        // Add key-value pair to the map
+        rfid_map[key] = value;
+      }
+    }
+    file.close();
+  } else {
+    Serial.print("Error opening file ");
+    Serial.println(filename);
+  }
+
+  return rfid_map;
+}
+
 String processor(const String &var)
 {
   if (var == "DIRECTORY")
@@ -273,56 +318,13 @@ void IRAM_ATTR rfid_interrupt()
 void readRFID()
 {
   rfid.PICC_ReadCardSerial();
-  Serial.print("Tag UID: ");
-  String uidString = getRFIDString(rfid.uid.uidByte);
-  Serial.println(uidString);
+  Serial.print("Card UID: ");
+  lastUid = getRFIDString(rfid.uid.uidByte);
+  Serial.println(lastUid);
+  //rfid.PICC_DumpDetailsToSerial(&(rfid.uid));
 
 
-  // Prepare key - all keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
-  MFRC522::MIFARE_Key key;
-  for (byte i = 0; i < 6; i++) key.keyByte[i] = 0xFF;
-
-  //some variables we need
-  byte buffer[42];  //data transfer buffer (16+2 bytes data+CRC)
-  byte size = sizeof(buffer);
-
-  uint8_t pageAddr = 0x05;  //In this example we will write/read 16 bytes (page 6,7,8 and 9).
-                            //Ultraligth mem = 16 pages. 4 bytes per page.  
-                            //Pages 0 to 4 are for special functions.  
-
-  MFRC522::StatusCode status;
-
-  rfid.PICC_DumpDetailsToSerial(&(rfid.uid));
-
-  //------------------------------------------- GET FIRST NAME
-  /*
-  status = rfid.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, 4, &key, &(rfid.uid)); //line 834 of MFRC522.cpp file
-  if (status != MFRC522::STATUS_OK) {
-    Serial.print(F("Authentication failed: "));
-    Serial.println(rfid.GetStatusCodeName(status));
-    return;
-  }
-
-  Serial.println("Auth");
-*/
-
-  // works only with mifare ultralight:
-  status = rfid.MIFARE_Read(pageAddr, buffer, &size);
-  if (status != MFRC522::STATUS_OK) {
-    Serial.print(F("Reading failed: "));
-    Serial.println(rfid.GetStatusCodeName(status));
-    return;
-  }
-
-  //Dump a byte array to Serial
-  for (byte i = 0; i < size; i++) {
-      Serial.write(buffer[i]);
-  }
-  Serial.println();
-  // ------------------------------
-  rfid.PICC_HaltA();
-
-  playSongByRFID(uidString);
+  playSongByRFID(lastUid);
   lastInteraction = millis();
 }
 
@@ -361,6 +363,8 @@ void setup()
   rootNode.buildDirectoryTree("/");
   rootNode.printDirectoryTree();
 
+  readDataFromFile(mapping_file.c_str());
+
   deactivateSD();
   activateRFID();
   Serial.println("RFID");
@@ -384,11 +388,19 @@ void setup()
 
   Serial.println("Audio initialized.");
 
+  lastVoltage = getBatteryVoltageMv();
+
+  Serial.print("Battery Voltage in mV: ");
+  Serial.println(lastVoltage);
+
     // first parameter is name of access point, second is the password
   AsyncWiFiManager wifiManager(&server, &dns);
 
   wifiManager.setTimeout(180);
 
+  Serial.println("Deactivating Brownout detector...");
+  WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0); //disable brownout detector
+
   if (wifiManager.autoConnect("HannaBox"))
   {
     server.on("/", HTTP_GET, [](AsyncWebServerRequest *request)
@@ -438,6 +450,9 @@ void setup()
     Serial.println("Wifi timed out. Fallback no Wifi.");
   }
 
+  Serial.println("Activating Brownout detector...");
+  WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 1); //enable brownout detector
+
   xTaskCreatePinnedToCore(
       loop2,      /* Function to implement the task */
       "RFIDTask", /* Name of the task */
@@ -459,7 +474,6 @@ void named_song_action(AsyncWebServerRequest *request)
   for (int i = 0; i < params; i++)
   {
     AsyncWebParameter *p = request->getParam(i);
-    Serial.printf("POST[%s]: %s\n", p->name().c_str(), p->value().c_str());
     if (p->name() == "title")
     {
       playSongByName(p->value());
@@ -477,7 +491,6 @@ void progress_action(AsyncWebServerRequest *request)
   for (int i = 0; i < params; i++)
   {
     AsyncWebParameter *p = request->getParam(i);
-    Serial.printf("POST[%s]: %s\n", p->name().c_str(), p->value().c_str());
     if (p->name() == "value")
     {
       audio.setAudioPlayPosition(atoi(p->value().c_str()));
@@ -495,7 +508,6 @@ void volume_action(AsyncWebServerRequest *request)
   for (int i = 0; i < params; i++)
   {
     AsyncWebParameter *p = request->getParam(i);
-    Serial.printf("POST[%s]: %s\n", p->name().c_str(), p->value().c_str());
     if (p->name() == "value")
     {
       audio.setVolume(atoi(p->value().c_str()));
